1. Field of the Invention
The present invention relates to a compressor, for a fluid, such as a refrigerant compressor used in an air-conditioning system.
2. Description of the Related Art
One example of a conventional compressor is described in Japanese Unexamined Patent Publication (Kokai) No. 2001-27177. The structure of this compressor is illustrated in FIG. 8. This compressor falls under the category of piston-type variable capacity compressor. The housing is comprised of a front housing 1, a cylinder block 2, and a rear housing 3. A plurality of pistons 7 are inserted into the plurality of cylinder bores 21 formed in the cylinder block 2, and are forced to engage in reciprocating motion by a common drive plate 5. The drive plate 5 is driven to rotate by a shaft 4. This drive plate 5 enables the tilt angle to be smoothly changed and thus enables the discharge capacity of the compressor to be continuously changed. Further, a plurality of mounting brackets 28 to secure this compressor with some objective equipment are formed integrally on the front housing 1 and cylinder block 2, respectively.
In order to integrate the front housing 1, cylinder block 2 and rear housing 3, this compressor has a plurality of through bolts 40 as used frequently in conventional compressors. In a conventional compressor, these through bolts 40 are provided with the outside of the housing in an exposed state. However, due to the plurality of through bolts 40, and as the diameter of the compressor becomes larger by at least the diameter of a through bolt 40, there arises a problem that the size of the compressor as a whole becomes larger.
An object of the present invention is to eliminate this problem in the related art by adding a novel configuration to the compressor, and to provide a much smaller compressor than a conventional compressor having the same degree of discharge capacity.
According to the invention, as a means for solving the problem described above, there is provided a compressor comprising a housing rotatably supporting a shaft and constituted from a plurality of parts aligning in the axial direction of the shaft and integrated with each other, a faucet joint portion provided between an end portion of one part of the housing and an end portion of another one part adjacent to the one part, and a screw connection portion formed on an inner and outer contact surfaces of the fitting portion, and wherein the one and other parts of the housing are connected and integrated with each other only by the screw connection portion formed with the fitting portion.
In this compressor, an end portion of one part among a plurality of parts constituting the housing and an end portion of another one part adjacent to the one part are integrated by a screw connection portion formed in a fitting portion provided between these two end portions. Therefore, it is possible to eliminate through bolts, etc. As the screw connection portion in the fitting portion can be formed without substantial increase of the diameter of the housing, the compressor can be made smaller as a whole.
In the compressor according to the present invention, at least one of mounting bracket, which can be adjusted in position with respect to the housing, can be provided with a mounting means for securing the housing with some objective equipment. This mounting bracket can be made slidable and adjustable with respect to the housing in at least a rotational direction. Therefore, when the position of a suction port or discharge port and the relative angle between a plurality of mounting brackets do not align with the corresponding position or angle on the objective equipment by using the screw connection portion formed in the fitting portion, the positional relationship between the compressor and objective equipment is readily adjustable by adjusting the position or angle of the mounting bracket with respect to the housing.
The present invention can be suitably applied to a piston-type variable capacity compressor, whereby the dimension of this compressor also can be made smaller as a whole.
These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:
Preferred embodiments of the present invention will be described in detail below while referring to the attached figures.
Corresponding to a feature of the invention, a female screw thread is formed on the inner surface at the rear end of the front housing 1. A rear housing 3 connected to such part of the front housing 1 has a generally flat and cylindrical shape and a male screw thread is formed on part of the outer peripheral portion thereof. Due to the connection of these male and female screw threads, a screw connection portion 24 is formed, and the rear housing 3 is secured at the rear end of the front housing 1 to close and seal. As a general consideration, at the end portions of a plurality of constituting parts of the housing such as front housing 1 and rear housing 3, in which they are connected each other, a fitting portion in which one and the other of them overlap in an inner and outer positional relationship is formed. Further, due to the screw threads formed on the inner and outer contact surfaces of the fitting portion, and directly engaged with each other, the screw connection portion 24 is constituted.
As a result, in the case of the first embodiment, the cylinder block 2 is pressed toward a stepped portion 1b formed inside of the front housing 1 and secured together. Also valve port plate 10, discharge valve 11 and suction valve 13 made of a thin sheet of spring steel are sandwiched between the cylinder block 2 and rear housing 3, and fixed there. Note that, to enhance the sealing performance between the front housing 1 and the rear housing 3, a seal ring (O-ring) 25 made of rubber is provided.
Corresponding to another feature of the invention, on the outer peripheral surface of the portion adjacent to the front end of the front housing 1 and the portion adjacent to the rear end of the same, at least one of mounting means 26 to attach the compressor to some objective equipment, for example, air-conditioning system, is provided. A shape and a construction of the mounting means 26 in the first embodiment are illustrated in FIG. 2. That is, the mounting means 26 in this example comprises a ring-shaped fixing band 27 made of elastic metal, etc., such as a steel sheet wrapping the outer periphery of the front housing 1, a block-type mounting bracket 28 made from metal or plastic, etc., integrated to suitable position of the fixing band 27, and a connecting portion 29 connecting the both ends of the fixing band 27 each other at a joint of the fixing band 27, etc.
The connecting portion 29 in this case comprises a pair of L-shaped portions formed at the both ends of the fixing band 27 at the joint, a bolt connecting those L-shaped portions each other, not shown, etc. Note that, in each mounting bracket 28, a hole 30 to insert the bolt for mounting, not shown, is formed. The mounting means 26 of the first embodiment having such a shape or construction is provided with front side and rear side of the front housing 1, respectively. Each mounting means 26 has two mounting brackets 28 at the symmetrical positions, however, it is of course that the present invention is not limited such a construction.
Next, an internal construction of the piston-type variable capacity compressor of the first embodiment will be explained. First, a suction chamber 31 is formed at the outer periphery at the inside of the rear housing 3, while a discharge chamber 32 is formed at the central portion of the same. A suction port 22 introducing a fluid to be compressed from an external portion is attached to the suction chamber 31, while a discharge port 23 introducing a compressed fluid to the external portion is attached to the discharge chamber 32.
Reference numeral 4 is a shaft for receiving rotational power from an external power source. A disk part 41 is formed integrally perpendicular to the same. A single radial direction arm 42 is provided to project, generally in the axial direction, from part of the outer periphery of the disk part 41. At the arm 42 are formed two guide grooves serving as cams, that is, a top guide groove 43 and a bottom guide groove 44, in predetermined shapes at predetermined positions at the top and bottom.
The shaft 4 is axially supported by the front housing 1 through radial bearings 402 and 404 and is axially supported by the front housing 1 in the axial direction as well through a thrust bearing 403 supporting the back surface of the disk part 41. Accordingly, the shaft 4 is supported only by the front housing 1 and it is not supported by the cylinder block 2. Note that shaft sealing devices 401 are provided at these bearing parts to prevent fluid from leaking from around the shaft 4 to the outside.
Reference numeral 5 is a drive plate (swash plate) generally in a disk shape. The drive plate 5 is provided with two radial direction arms 51 projecting from its back surface toward the disk part 41 and supports two pins 52 and 53 between the two arms 51. These pins 52 and 53 are inserted into the top guide groove 43 and bottom guide groove 44 formed in the above-mentioned arm 42 at the shaft 4 side to be slidably engaged with the same. Due to this, the drive plate 5 can rotate together with the shaft 4 and can tilt with respect to the shaft 4.
The shaft part 5b of the drive plate 5 has fitted on it a shoe holding plate (retainer) 6 having an opening at its center. This is rotatably connected with the drive plate 5 by a drive thrust bearing 500, a holding plate thrust bearing 601 and a holding nut 9. The shoe holding plate 6 grips the later-explained shoes 8 and drive thrust bearing 500 to the drive plate 5 and is used to guide movement of the shoes 8 in the radial direction. Note that the shaft part 5b of the drive plate 5 is provided with a male thread for screwing into the holding nut 9.
The specific shape of the shoe holding plate 6 in the illustrated embodiment will be clear if FIG. 3 and
Each shoe guide groove 6c has slidably engaged with it a shoe body 8a, of a shape close to a closed bottom cylinder, of a shoe 8, having abrasion resistance, of the shape shown in FIG. 4. The shoe holding plate 6 is connected rotatably relative to the drive plate 5 but, as the shoe body 8a fitted on the spherical end 7a of the piston 7 is engaged with the U-shaped shoe guide groove 6c of the shoe holding plate 6, rotation of the shoe holding plate 6 is prevented and only a rocking motion is performed along with a tilted rotary motion of the drive plate 5.
As shown in FIG. 1 and
The holding nut 9 screwed over the male thread formed at the shaft part 5b of the drive plate 5 presses the shoe holding plate 6 toward the drive thrust bearing 500 and drive plate 5 through the holding plate thrust bearing 601. Due to this, the shoe holding plate 6 simultaneously presses the plurality of shoes 8 on to the drive thrust bearing 500. In this way, the thrust bearing 500, the plurality of shoes 8, the shoe holding plate 6, and the holding plate thrust bearing 601 are assembled on the drive plate 5. Note that reference numerals 501 shown in
Reference numeral 10 is a valve port plate having at least one each of a suction port 10a and discharge port 10b passing through the same at positions corresponding to each cylinder bore 21. Each suction port 10a of the valve port plate 10 is closed off from the suction chamber 31 of the rear housing 3 from the cylinder bore 21 side by part of the suction valve 13 made of a single thin sheet of spring steel. Each discharge port 10b is closed off from the discharge chamber 32 side in the rear housing 3 again by part of the discharge valve 11 made of a single thin sheet of spring steel. The discharge valve 11 is simultaneously fastened when a valve holder 12 protecting it is screwed to a valve port plate 10 by a bolt 14. Further, the valve port plate 10 and suction valve 13 are fastened by being gripped between the front housing 1 and cylinder block 2 and the rear housing 3 when these are fastened together as a whole.
As explained above, in the compressor of the first embodiment, as the front housing 1 and the rear housing 3 are detachably integrated by the screw connection portion 24, in comparison with a conventional compressor provided a plurality of through bolts at the outside or the inside of a housing, it is possible to reduce the diameter of the housing 1, at least by the part of the plurality of through bolts. So there is an advantage that the compressor can be made smaller as a whole.
On the other hand, if the mounting brackets 28 to attach the compressor to some objective equipment such as air-conditioning system are directly provided with the external surface of the front housing 1, a relative and positional relationship between the front housing 1 and the objective equipment is decided definitely. However, when the rear housing 3 is attached to the front housing 1 by the screw connection portion 24, as the physical (positional) relationship in the rotational direction between both housings 1 and 3 is indefinite, a problem that the positions of the suction port 22 and discharge port 23 do not coincide with the positions of the corresponding parts in the objective equipment occurs.
In the first embodiment, to solve this problem, the relative and positional relationship in the rotational direction and the axial direction between the front housing 1 and mounting means 26 is adjustable. That is, after the mounting bracket 28 of the mounting means 26 was attached to the corresponding portion of the objective equipment, bolts of the connecting portion 29, etc., are loosened, and the front housing 1 is slid in the fixing band 27 in the rotational direction or the axial direction and the suction port 22 and the discharge port 23 are coincided with the corresponding portions of the objective equipment and coupled respectively. Then, due to the connecting portion 29 being in such a state, the positional relationship between the mounting means 26 and the front housing 1 is fixed.
Next, the operation of the drive plate type variable capacity compressor of the first embodiment will be explained.
When the shaft 4 is driven to rotate by an external power source such as an internal combustion engine or motor mounted in a vehicle, the drive plate 5 connected to the disk part 41 of the shaft 4 through the arm 42, top and bottom guide grooves 43 and 44, two pins 52 and 53, and two arms 51 rotate together with the shaft 4. The shoe holding plate 6, however, is supported with respect to the drive plate 5 through the holding plate thrust bearing 601, and the plurality of shoes 8 engaged with the shoe guide grooves 6c engage with the spherical ends 7a of the pistons 7, so the plate does not rotate. Therefore, only when the drive plate 5 is tilted with respect to the imaginary plane perpendicular to the shaft 4, the shoe holding plate 6 engages in rocking motion of a magnitude corresponding to its tilt angle while gripping the drive thrust bearing 500 and plurality of shoes 8 with the drive plate 5. Due to this, the plurality of shoes 8 gripped between the shoe holding plate 6 and the drive plate 6 through the drive thrust bearing 500 and the plurality of pistons 7 connected with the same engage in a reciprocating motion in the cylinder bores 21.
In the case of the first embodiment, when the two pins 52 and 53 move by sliding in the top guide groove 43 and bottom guide groove 44 at the shaft 4 side, the drive plate 5 and the shoe holding plate 6 change in tilt angle with respect to a supposed plane perpendicular to the shaft 4, so the strokes of all of the pistons 7 change simultaneously by exactly the same amounts. Due to this, the discharge capacity of the compressor changes steplessly.
The working chamber C formed at the top face of each piston in the suction stroke among the plurality of pistons 7 expands and reaches a low pressure, so the fluid to be compressed in the suction chamber 31, for example, the refrigerant of an air-conditioning system, pushes open the suction valve 13 provided at the suction port 10a of the valve port plate 10 and flows in. As opposed to this, the working chamber C formed at the top face of each piston 7 in the compression stroke contracts, so the fluid inside it is compressed and becomes a high pressure and pushes open the discharge valve 11 provided at the discharge port 10b of the valve port plate 10 to be discharged to the discharge chamber 32. The discharge capacity in this case is generally proportional to the length of the stroke of the piston 7 determined by the tilt angle of the drive plate 5 and the shoe holding plate 6.
By changing the tilt angle of the drive plate 5 and the shoe holding plate 6 in this way, the discharge capacity of the compressor changes, so the discharge capacity may be controlled in the compressor of the first embodiment by changing the pressure in the front housing chamber 1a forming the back pressure of all of the pistons 7 using a not shown pressure control valve etc. Normally, a pressure intermediate between the high pressure of the discharge chamber 32 and the low pressure of the suction chamber 31 is introduced from the pressure control valve.
If the pressure in the front housing chamber 1a, that is, the back pressure of all of the pistons 7 is raised, the state of balance with the pressure in the working chamber C formed at the top face of each piston 7 is lost, and the average position of the pistons 7 in the reciprocating motion moves toward a position close to the valve port plate 10 until a new state of balance is obtained. Due to this, the strokes of all of the pistons 7 become smaller, so the discharge capacity of the compressor is smoothly reduced.
As opposed to this, if a not shown pressure control valve is operated to reduce the pressure in the front housing chamber la, the back pressure acting on the pistons 7 becomes smaller, so the strokes of all of the pistons 7 become larger all together and the discharge capacity of the compressor becomes smoothly larger.
Next, a second embodiment of a compressor of the present invention shown in FIG. 5 and
The difference between the compressor of the second embodiment and the compressor of the first embodiment is in the mounting means 26. In the second embodiment, the mounting means 26 provided on the front end portion of the front housing 1 differs from the mounting means 26 provided on the rear end portion of the same. The mounting means 26 provided on the front end portion comprises a thin and deep dish-shaped cover 33 attached so as to cover the front end surface of the front housing 1 of the compressor, at least one mounting bracket 28 integrated with a suitable position on the cover 33, and a plurality of bolts 34 securing the cover 33 to the front end surface of the front housing 1. A plurality of arcuate slits 35 to insert the bolts 34 are formed in the front surface of the cover 33, also a plurality of female screw thread holes 36 engaging with the bolts 34 inserted through the slits 35 are formed in the front end surface of the front housing 1. The mounting bracket 28 is the same as in the first embodiment and a hole 30 is formed.
In the second embodiment, a screw connection portion 24 is formed at a fitting portion between an outer peripheral surface at the rear end of a cylindrical front housing 1 and the inner peripheral surface of a short cylindrical portion 37 integrally formed to project from a rear housing 3 toward the front side, whereby the front housing 1 and the rear housing 3 are integrated with each other. Accordingly, the positional relationship between the front housing 1 and the rear housing 3 in the second embodiment is opposite to the case in the first embodiment. However, also in this case, as a screw connection portion 24 is used, in comparison with a conventional compressor using through bolts, the diameter of the housing is reduced, and the compressor of the second embodiment can be made smaller, as a whole.
The mounting means 26 of the compressor which one arranged at the rear end of the front housing 1, is formed by using the rear housing 3. That is, in the second embodiment, at least one mounting bracket 28 is formed integrally with the outer peripheral surface of the rear housing 3 having a suction port 22 and a discharge port 23. Therefore, with respect to the mounting means 26 provided with rear housing 3, there is no particular need to adjust the positional relationship between the compressor and the objective equipment.
In this case, an adjustment of the positional relationship between front housing 1 and the mounting means 26 arranged at the front end of the front housing 1 only is needed. That is because, in a state that the rear housing 3 is integrated with the front housing 1 by the screw connection portion 24 formed on the fitting portion, the positional relationship in the rotational direction between the front housing 1 and rear housing 3 is unspecified. Therefore, if a mounting bracket 28 is fixed to the front housing 1, a case that the mounting bracket 28 does not align with the same of the rear housing 3 may occured.
Therefore, in the second embodiment, the mounting means 26 provided with the front end of the front housing 1 is adjusted in the rotational direction to the front housing 1 itself. By firstly loosing bolts 34, then, by rotating the cover 33 to the front housing 1, in the range of the arcuate slits 35 formed in the cover 33, this adjustment can be easily carried out. The bolts 34 are secured again after the adjustment is finished. Therefore, when the screw connection portion 24 is secured, the mounting means 26 of the front end of the front housing 1 can be easily adjusted in the rotational direction even if the mounting means 26 on the cover 33 does not align with the same on the rear housing 3, and thereby the suction port 22 and discharge port 23 can be aligned with corresponding portions of the objective equipment.
In the case of the third embodiment, all of the mounting brackets 28 as the mounting means 26 of the front side and the rear side are provided at the front end and the rear end of the cylindrical trunk portion 38, which is integrated with the rear housing 3 attached a suction port 22 and a discharge port 23 thereto. The screw connection portion 24 having a fear caused variation of relatively positional relationship in rotational direction is provided between the front end of the cylindrical trunk portion 38 and the front housing 1 having no mounting bracket. Therefore, there is no need to provide any adjusting means for positional relationship between the mounting means 26 and the suction port 22 and discharge port 23. Further, even if the positional relationship in a rotational direction between the cylindrical trunk portion 38 and front housing 1 is varied due to screw up the screw connection portion 24, as a thrust bearing 403 is provided with this compressor, no problem will be caused on the operation of the compressor.
Also in the case of the third embodiment, as the front housing 1 is integrated with the rear housing 3 by the screw connection portion 24 formed in the fitting portion, the diameter of the compressor is reduced because there is no need for through bolts, and the compressor can be made smaller as a whole. In spite of the aforementioned fact, no problem is caused by the screw connection portion 24, as all of the mounting means 26 are provided with the side of the rear housing 3 integrated with the suction port 22 and discharge port 23.
Note that, all of the illustrated embodiments are related to the piston-type variable capacity compressor. However, it is obvious that the key parts of the present invention can be adapted to not only the piston-type variable capacity compressor but also a piston-type constant capacity compressor or another type of compressor. It is, of course, possible that, in this case, that the advantage of the present invention, that the compressor can be made smaller as a whole due to the elimination of through bolts, is obtained.
Number | Date | Country | Kind |
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2002-038055 | Feb 2002 | JP | national |
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Number | Date | Country | |
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20030156951 A1 | Aug 2003 | US |